My research is focused on the in situ analysis of surfaces and interfaces facilitating synchrotron radiation for
1) the fundamental understanding of surface processes,
2) materials characterization and synthesis,
3) the analysis of heterogeneous catalysis,
4) the development of new in situ techniques.
In the following his main achievements and projects of the past years are summarized.
Liquid organic hydrogen carriers
Studying LOHCs is motivated by one of the grand present challenges of mankind, namely the storage of energy. Among several approaches, one potential solution is “chemical storage” of hydrogen using Liquid Organic Hydrogen Carrier (LOHC) materials. These substances are high boiling organic molecules, which can be reversibly hydrogenated and dehydrogenated using heterogeneous catalysts.
Despite the high relevance of such systems, the molecular level understanding of the catalytic dehydrogenation and hydrogenation of LOHCs is still at its infancy. This is partly due to the size of the molecules (forty and more atoms) which makes them a major challenge for surface science methods. Nevertheless, the Papp group demonstrated that by an in situ XPS study of such molecules on model catalysts, one can obtain detailed insights into the mechanisms of dehydrogenation and also of relevant side-reactions, at the molecular level. See e.g.
C. Papp et al. Chem. Rec. 14 (2014) 879.
E. Freiberger, C. Papp et al. Chem. Phys. Lett. 797 (2022) 139595.
V. Schwaab, C. Papp et al. J. Phys Chem. C, 127 (2023) 11058.
Growth and Chemical Modification of 2D materials
2D materials are promising candidates for future electronics. Their high potential for applications stems from their outstanding properties such as their electronic structure, their mechanic staibility. The growth of g2D materials on metal surfaces has received significant attention as a potential low energy route for their production. Besides graphene and hexagonal boron nitride, materials such as borophene and phosphorene are under investgation.
The aim of these studies is the synthesis and modifcation of new materials for applications as electronics, sensors or in heterogeneous catalysis. See e.g.
C. Papp Cat. Lett. 147 (2017) 2683
F. Späth, C. Papp et al. 2D Materials 4 (2017) 35026
E. Freiberger, C. Papp et al. Nanotechnology, 35 (2024)145703.
Liquid metals / alloys (SFB 1452):
Liquid metals such as gallium and alloys of gallium with catalytically active metals are a novel topic from the fundamental side, since they allow for studying liquid metallic systems in an UHV environment. Additionally, they are of interest for heterogeneous catalysis as they have been shown to be effective catalysts with only a fraction of the often expensive transition metal content. These systems therefore promise new and fascinating insights to the liquid / gas interface, and they allow for studying the influence of low concentrations of the catalytically active metal in an inert matrix. Thus, typical effects such as ligand and ensemble effects as well as the changes in the electronic structure can be studied in a liquid system.
Taccardi, Papp et al. Nat. Chem. 10 (2017) 862;
Wittkämper, Papp et al. J. Chem. Phys. 153 (2020) 104702
H. Wittkämper, C. Papp et al. Sci. Rep. 13 (2023) 4458.
M. Moritz et al. ACS Catalysis (2024) accepted.